The following relates generally to wireless communication, and more specifically to scheduling assignment (SA) transmissions in device-to-device (D2D) communications.
Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, and orthogonal frequency division multiple access (OFDMA) systems, (e.g., a Long Term Evolution (LTE) system).
By way of example, a wireless multiple-access communication system may include a number of base stations, each simultaneously supporting communication for multiple communication devices, otherwise known as user equipment (UE). A base station may communicate with UEs on downlink channels (e.g., for transmissions from a base station to a UE) and uplink channels (e.g., for transmissions from a UE to a base station). UEs may communicate directly with each other using D2D communications over a direct D2D wireless link.
Various implementations provide for D2D communications in band(s) of a licensed frequency spectrum, an unlicensed frequency spectrum, or combinations thereof. Communications in the unlicensed frequency spectrum band, however, may comply with various requirements regarding resource utilization, medium access procedures, etc. Moreover, D2D communications have established protocols that may, at times, result in relatively long latency of reception of packets. For many D2D UEs communications may be relatively latency insensitive. In cases where communications are sensitive to latency, however, such relatively long latency may be undesirable.